Summary. Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the major risk factors for hepatocellular carcinoma (HCC). We examined trends in the incidence of HCC among a population-based cohort of people infected with HBV or HCV. HBV and HCV cases notified to the New South Wales Health Department between 1992 and 2007 were linked to the Central Cancer Registry, Registry of Births, Deaths and Marriages, and National HIV/AIDS Registries. Crude HCC incidence rates were estimated using person-time methodology.

Age-standardized incidence rates were calculated using the 2001 Australian population. Trends in incidence were examined using join point regression models. Between 1992 and 2007, 1201 people had a linked HCC record: 556 of those with HBV; 592 with HCV; 45 with HBV/HCV co-infection; and 8 with HIV co-infection. The overall age-standardized HCC incidence rates declined non-significantly from 148.0 (95% confidence intervals (CI) 63.7, 287.4) per 100 000 population in 1995 to 101.2 (95% CI 67.3, 144.6) in 2007 among the HBV monoinfected group and significantly from 151.8 (95% CI 62.4, 299.8) per 100 000 population to 75.3 (95% CI 50.8, 105.5) among the HCV monoinfected group. However, incidence rates in the HCV monoinfected group progressively increased from the period 1992-1997 to 2004-2007 when adjusted for age, sex, and birth cohort, and the total number of cases per annum continued to increase.

Despite declines in the age-adjusted incidence rates of HCC over time, the absolute number of cases increased likely due to the ageing cohort and an increasing prevalence of both hepatitis B and C in Australia.